Muhammad Ali: 'The Greatest' at 70

Golden moment – Cassius Clay, later to become known as Muhammad Ali, rose to prominence at the 1960 Olympic Games in Rome, where he claimed a boxing gold medal in the light heavyweight division.

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Muhammad Ali: 'The Greatest' at 706 photos

High five – Ali boldly predicted how many rounds it would take him to knock out British boxer Henry Cooper ahead of their bout in London in 1963. The fight was stopped in the fifth round as Cooper was bleeding heavily from a cut around his eye and Ali was declared the winner. Cooper died in May 2011.

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Muhammad Ali: 'The Greatest' at 706 photos

I'm the greatest – Ali first became a world champion in 1964, when he was still known as Cassius Clay. He upset the odds to defeat reigning champion Sonny Liston, a result which prompted him to yell "I'm the greatest" at gathered reporters.

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Muhammad Ali: 'The Greatest' at 706 photos

Rumble in the Jungle – In 1974, Ali took part in one of the most famous world championship fights in the history of boxing. He took on reigning champion George Foreman in Zaire, in a fight which was dubbed the "Rumble in the Jungle." Ali emerged victorious after flooring Foreman in the eighth round.

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Muhammad Ali: 'The Greatest' at 706 photos

Let the Games begin – Ali provided one of the iconic images of the 1996 Atlanta Olympics when he lit the Olympic flame to officially declare the Games open.

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Muhammad Ali: 'The Greatest' at 706 photos

Regaining gold – In addition to lighting the flame, Ali also received a replacement gold medal for the one he had won 36 years earlier. Ali tossed the original into the Ohio River after being refused entry to a restaurant.

Story highlights

Tris Dixon, editor of Boxing News, tells CNN there will never be another Ali

Ali was involved in some of the most memorable fights in the sport's history

He won the iconic "Thrilla in Manilla" and "Rumble in the Jungle" bouts

There are not many sportsmen who can call themselves "The Greatest" and not be greeted with ridicule -- former world heavyweight champion Muhammad Ali is one of the few who can lay claim to such unrivaled supremacy.

The Kentucky native turned 70 Tuesday, prompting people from across the world to pay tribute to a former boxer who has shown his fighting spirit both inside and outside the ring during an extraordinary life.

"Everything that Ali has done and stood for, you can only aspire to be like him," Tris Dixon, editor of Boxing News, told CNN. "He was the king in the biggest and best era of heavyweight champions."

Ali rose to prominence at the 1960 Olympics in Rome, where he won a gold medal in the light heavyweight division fighting under his birth name of Cassius Clay.

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Muhammad Ali turns 70

Ali's boxing career is perhaps best remembered for two of his most famous fights against two of his fiercest rivals.

In Zaire in October 1974, Ali upset the odds to reclaim the WBA and WBC world heavyweight titles against George Foreman in a bout dubbed the "Rumble in the Jungle."

A year later, Ali squared off against the late Joe Frazier for the third time in his career.

The fight in the Philippines, known as the "Thrilla in Manilla," lasted 14 devastating rounds, with Ali taking glory when Frazier was unable to make the bell at the start of the 15th.

But, for Dixon, it was a third-round knockout of Cleveland Williams in a 1966 fight for the world heavyweight title which best displayed Ali's boxing talents.

"Against Cleveland Williams, that was Ali at his best," he explained. "It was utter poetry. It was just immense ... it was punch perfect against a world-class opponent."

Ali eventually retired in 1981 with a record of 56 wins, 37 by knockout, and five losses in 61 bouts.

He began an altogether different fight in 1984, when he was diagnosed with neurological disorder Parkinson's syndrome.

In 1996, at the age of 54, Ali provided one of the iconic images of the Atlanta Olympics when he lit the torch to declare the Games open.

Ali also received a replacement gold medal for the one he had won 36 years earlier, having thrown the original into the Ohio River after being refused entry to a restaurant.

Despite Ali's advancing years, Dixon claimed his legacy is still as strong and relevant as it has ever been.

"There will never be anyone like Ali," he said. "There will be people like Tiger Woods and Michael Jordan who reflect their times, but there will never be someone who means as much to the world and the cultural landscape as much as Ali did."